Dampers are often situated in ducts of HVAC systems to regulate the flow of air. A damper is often provided as a flap/blade which pivots or otherwise moves on a shaft within an airflow passage to provide varying degrees of obstruction to airflow. The damper may automatically move in response to air pressure, typically with weights, springs, or other resistances being affixed to the damper blade (or damper shaft) to provide a desired degree of resistance to motion (usually a desired degree of resistance to the damper blade's opening). A regulator may be provided outside the duct surrounding the airflow passage to allow adjustment of the damper blade's position, and thus the degree to which the damper blade obstructs the airflow passage. Alternatively or additionally the regulator may allow adjustment of the damper blade's motion resistance. As examples, a manual regulator is often provided as handle which actuates the damper shaft to allow manual pivoting of the damper blade, or which adjusts spring tension to adjust the damper blade's motion resistance. Automatic regulators typically act in a similar manner, but use servomotors, solenoids, or other actuators to adjust damper blade position and/or damper blade motion resistance. The reader is directed to U.S. Pat. No. 5,249,596 to Hickenlooper, III et al., and to U.S. Pat. No. 9,032,993 to Barton et al., for further background concerning dampers.
HVAC systems can be optimized by use of dampers that provide the desired degree of airflow in response to upstream pressure (or more accurately, in response to the difference in upstream pressure versus downstream pressure). As an example, the Barton et al. patent describes a regulator that provides a damper with a relatively “flat” flow vs. pressure response, wherein the damper opens when a certain “crack” pressure is reached, and provides relatively constant resistance to airflow thereafter (i.e., a relatively constant pressure drop across the damper) regardless of the amount of airflow. This is in contrast with typical damper regulators, wherein greater airflow can only be achieved with greater pressure. This effect is illustrated by Hickenlooper, wherein the regulator spring-loads the damper: greater opening of the damper (and thus greater airflow) requires greater pressure. This can increase the load encountered by blowers and other HVAC air driving equipment, shortening the lifespan of such equipment, as well as increasing the noise generated by the HVAC system's ductwork. While the regulator of Barton et al. can help alleviate these problems, the Barton et al. regulator is significantly more complex and expensive than a regulator such as that of Hickenlooper, and thus there is a desire for alternative regulators which provide better flow vs. pressure response, and/or which more generally allow for greater customization of the flow vs. pressure response.